| From 2f0580cece3ab2baaf9214f434c7146e389566a4 Mon Sep 17 00:00:00 2001 |
| From: Nathan Sidwell <nathan@codesourcery.com> |
| Date: Fri, 22 Mar 2013 17:48:51 +0100 |
| Subject: [PATCH] Fix some fragileness in dlopen/do_dlopen wrapper & worker |
| pair. |
| |
| do_dlopen contains __builtin_return_address to determine from |
| whence it was called, and uses that to determine which dynamic |
| object's data it should use to start the search. (In the bug I was |
| tracking, this related to whether the application's RPATH was used or |
| not.) For that to work, it has to have been inlined into the wrapper |
| function. |
| |
| As it happens, it wasn't being inlined. That's an unfortunate compiler |
| behaviour, but it isn't wrong and shouldn't have caused dlopen to fail. |
| |
| This patch changes things so the wrapper function determines the |
| return address, and passes it to the worker. If the worker's inlined, |
| the generated code should be exactly the same as before. |
| |
| Signed-off-by: Nathan Sidwell <nathan@codesourcery.com> |
| Signed-off-by: Bernd Schmidt <bernds@codesourcery.com> |
| Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com> |
| --- |
| ldso/libdl/libdl.c | 8 +++----- |
| 1 file changed, 3 insertions(+), 5 deletions(-) |
| |
| diff --git a/ldso/libdl/libdl.c b/ldso/libdl/libdl.c |
| index 71ade1f..018c720 100644 |
| --- a/ldso/libdl/libdl.c |
| +++ b/ldso/libdl/libdl.c |
| @@ -296,11 +296,10 @@ static ptrdiff_t _dl_build_local_scope (struct elf_resolve **list, |
| return p - list; |
| } |
| |
| -static void *do_dlopen(const char *libname, int flag) |
| +static void *do_dlopen(const char *libname, int flag, ElfW(Addr) from) |
| { |
| struct elf_resolve *tpnt, *tfrom; |
| struct dyn_elf *dyn_chain, *rpnt = NULL, *dyn_ptr, *relro_ptr, *handle; |
| - ElfW(Addr) from; |
| struct elf_resolve *tpnt1; |
| void (*dl_brk) (void); |
| int now_flag; |
| @@ -320,8 +319,6 @@ static void *do_dlopen(const char *libname, int flag) |
| return NULL; |
| } |
| |
| - from = (ElfW(Addr)) __builtin_return_address(0); |
| - |
| if (!_dl_init) { |
| _dl_init = true; |
| _dl_malloc_function = malloc; |
| @@ -661,7 +658,8 @@ void *dlopen(const char *libname, int flag) |
| void *ret; |
| |
| __UCLIBC_MUTEX_CONDITIONAL_LOCK(_dl_mutex, 1); |
| - ret = do_dlopen(libname, flag); |
| + ret = do_dlopen(libname, flag, |
| + (ElfW(Addr)) __builtin_return_address(0)); |
| __UCLIBC_MUTEX_CONDITIONAL_UNLOCK(_dl_mutex, 1); |
| |
| return ret; |
| -- |
| 1.7.10.4 |
| |
